Hi O_F

I have the same problem, and quick answer to your question is no, there are some that are reverting back to an older firmware version with limited success but in our case we have brought new units which in all honesty why would you downgrade the firmware (that's if you can) so my answers are hold out until some cleaver chap comes up with a new way around it,
Or in my case, in desperation have to buy a genuine map from Garmin, but please note downloads from Garmin don't have Junction views or any other add on features,
But the good news is you can add the JVC file yourself after the map installation, anyway hope this helps.